Existing water-cooled internal combustion engine cylinder heads, especially the cylinder heads of multi-cylinder engines, have a cooling water chamber which has a complicated shape and is closed in a cylinder head housing. Because of the complicated shape, nowadays the cylinder heads are manufactured in a complex casting process with sand cores. In such a casting process, it is difficult to remove the sand cores and to clean the castings so that the castings often present rather rough surfaces. And, such a casting process is of high cost and trends to pollute environment. Therefore, there is a need to create a new configuration and structure of water-cooled internal combustion engine cylinder head, so as to manufacture water-cooled internal combustion engine cylinder heads in a pressure casting (or die casting) process using light alloys.
CN202991254U and CN103452690A discloses a solution of manufacturing a two-part internal combustion engine cylinder head in which an upper cylinder head part and a lower cylinder head part are manufactured separately and then the upper part and lower part are jointed into an integral cylinder head by welding, adhering, screw-fastening or riveting process. Thus, it provides a solution for manufacturing a basic configuration and structure of the water-cooled cylinder head by die casting process using light alloys. However, such a cylinder head still has some deficiencies in design and manufacture process that will be pointed out in detail hereinafter.
As far as welding is concerned, it is done in this way: firstly, a first workpiece is inserted into a hole corresponding thereto in a second workpiece, and then by welding the two workpieces at the edge of the hole mouth, the two workpieces are welded together and into a welded structure assembly. In the existing art, welding is conducted along and in the gap at the hole mouth and between the first workpiece and second workpiece so as to form an endless and sealing weld joint along the hole mouth edge, for example, by arc welding, gas welding, friction stir welding, or flash butt welding, thereby the two workpieces are jointed together and the gap between them at the hole mouths is sealed. However, in the case that the junction interface of the two workpieces is in a narrow space at the hole mouth, it is very difficult for a welding gun to reach the junction interface to conduct welding. Further, in the case that the junction interface is in a narrow space and it is necessary to rapidly complete welding of densely-disposed plural junction interfaces between the two workpieces at the hole mouths, it is very hard for the tools for arc welding or gas welding to reach the junction interfaces so that it is impossible to conduct high-speed welding. Likewise, it is very difficult for the stirring needle jig of friction stir welding to be inserted into a narrow space to follow a stirring track. As to flash butt welding, for welding densely-disposed plural junction interfaces between two workpieces at the hole mouths, the welding process is very difficult, welding cost will be very high, and deformation of workpieces caused by welding is hard to be solved. Even if the welding processes mentioned above could be carried out successfully, the surfaces of the weld joints obtained would be very rough or uneven, so that they need to be ground. As well known, grinding is time-consuming and its final result may be unsatisfactory.
CN101992348A discloses a surface junction configuration between a first workpiece and a second workpiece as well as a friction welding method therefor, wherein the adjoining surfaces of the two workpieces form a welded junction interface by relatively reciprocating or rotating motion so as to heat the adjoining surfaces by friction heat to a friction welding temperature. The adjoining surfaces are stopped under a pressure, and then to be cooled. CN102537146A discloses a friction stir welding configuration used for the bottom of a disc brake. CN1651776A discloses a rotary friction welding configuration used for a cross joint of tubular workpieces. CN1840886B discloses a rotary friction welding configuration between common rail parts of a diesel engine. CN101157158A discloses a rotary friction welding configuration between a steel workpiece and an aluminum workpiece. CN100553850C discloses a method and a system of inertia friction welding. CN103260808A discloses a technical solution for electric heating, sliding and press bonding between separately pressure-casted parts of a cylinder head. All the above-mentioned workpiece configurations in the prior arts, so far, still cannot be directly applied to weld densely-disposed plural junction interfaces at the hole mouths between a first workpiece and a second workpiece, the process requires to complete welding at a high speed in a narrow space. Therefore, there is an urgent need to create a new welding configuration and structure in which it is possible to insert a first workpiece in a hole corresponding thereto in a second workpiece and to weld the two workpieces together at their hole mouths, meanwhile, welding is carried out quickly, economically, reliably, and aesthetically.
CN102678352A discloses a water-cooled internal combustion engine cylinder head fitted with a sparking plug for ignition, fuel is injected into an intake duct and mixed with fresh air therein, and then enters an engine cylinder through an intake valve and is ignited and burned in the cylinder. CN102251873A discloses a water-cooled internal combustion engine cylinder head with a centrally disposed direct-injection fuel injector, the fuel injector and the sparking plug are positioned in a central concave portion of the cylinder head. CN102865154A discloses a water-cooled internal combustion engine cylinder head with a tilted direct-injection fuel injector, the fuel injector is mounted in a side wall of the water-cooled cylinder head.
As mentioned above, CN202991254U and CN103452690A discloses a technical solution of a water-cooled cylinder head in which the cylinder head is integrated by an upper part and a lower part which are manufactured separately, and the two parts are joined together to form a integrated water-cooled cylinder head by a process such as welding, adhering, screw-fastening and/or riveting. This makes the configuration and structure of multi-part water-cooled cylinder head get further improvement and provides a basic configuration and structure solution of a water-cooled cylinder head that can be formed of light alloys by die-casting. However, in welding cylinder head bolt receiving holes, a fuel injector receiving hole, intake and exhaust valve stem receiving holes, intake and exhaust duct holes and a sparking plug receiving hole of a cylinder head formed of aluminum alloys or magnesium alloys, their upper hole portions and their lower hole portions respectively in the upper cylinder head part and the lower cylinder head part are connected with each other. In the case that the upper cylinder head part and lower cylinder head part are welded together into a cylinder head by welding, such as arc welding, gas welding, friction stir welding and flash butt welding, between the upper cylinder head part and lower cylinder head part, it is impossible to solve the technical problems, such as narrow spaces for welding, high-speed welding, little deformation, reliable sealing and aesthetical appearance. Therefore, there is an urgent need to create a new welding configuration between an upper cylinder head part and a lower cylinder head part of a water-cooled internal combustion engine cylinder head, which allows to weld the upper cylinder head part and the lower cylinder head part into an integrated cylinder head of a water-cooled internal combustion engine by using a quick, economic and reliable welding process.